It's hard to make
It's hard to make the transition from crazy to depressed, because the main character's character is very quiet, and also very shy. The movie is very slow, and the two main characters are relatively quiet, and it's kind of hard to feel the need to switch between them. A lot of the comedy is devoted to the main character's struggle with his identity. The movie is very dark, and this is why I haven't seen the movie in a while.
It's hard to make an accurate comparison to the film's best performances, but it's a shame they didn't bring in a better actor to perform the role. It's hard to imagine a better movie than this.